Землетрясение магнитудой 8 произошло на юге Мексики. Затем более шестидесяти афтершоков.
О нестандартности землетрясения в Мексико.
Для себя отмечаю, что всюду работают востребованные русские специалисты и ученые.
When Vlad Manea heard about the deadly magnitude-8.2 earthquake that struck the coast of Mexico’s Chiapas state on 7 September, he was stunned, but not altogether surprised. A geophysicist at the National Autonomous University of Mexico (UNAM) in Juriquilla, Manea is one of only a handful of earth scientists who study seismic activity in the region. For more than a century, there had been little activity to study—precisely why Manea thought the area could be due for a big one.
The epicenter of the quake, which struck just before midnight local time, was just southeast of the Tehuantepec gap, a 125-kilometer-long stretch of Mexico’s Pacific coast that has been seismically silent since record-keeping began more than a century ago. All along that coast, the ocean’s tectonic plates meet the continental North American plate and are forced underneath it. Violent earthquakes mark the release of built-up pressure between the grinding plates. But the ruptures have somehow avoided the Tehuantepec gap and the Guerrero gap, more than 500 kilometers to the northwest.
He concedes, though, that the quake’s effect on the gap is hard to judge, because of its unusual origin. Most big Mexican earthquakes occur right along the interface between the colliding Cocos and North American plates. But this rupture began 70 kilometers down, within the Cocos plate itself, and rose up before stopping at about 40 kilometers’ depth, likely at the plate interface. “It’s not the same fault that they’re expecting [to close] the Tehuantepec gap,” says Joann Stock, a seismologist at the California Institute of Technology in Pasadena.
That leaves the future risk of the Tehuantepec gap unclear. In fact, Stock says, last week’s quake might have even added stress at the gap and increased chances for future slipping. But, she adds, the depth of the shaking had at least one benefit: The rupture didn’t break through all the way to the ocean floor, which dampened tsunamis. The resulting waves in Chiapas and Oaxaca were only 2 to 3 meters high.
Vladimir Kostoglodov, a seismologist at UNAM in Mexico City, says he is fielding requests for data from researchers around the world who want to investigate this “extremely strange” earthquake and its aftermath. “It’s worth making a big effort to learn what’s happening,” he says. “This might happen in other subduction zones in other parts of the world.”